1. Field of the Invention
The present invention relates to a side impact airbag apparatus mounted on a vehicle seat for deployment forward between a lateral side of vehicle and an occupant.
2. Description of the Related Art
Such an airbag apparatus is known in JP 10-338099 by way of example. The airbag apparatus includes a planar airbag that is made by connecting outer peripheral edges of two generally identical panels together. The airbag is folded up into a compact configuration from a flattened state through a vertical contracting step and a horizontal contracting step. In order for the airbag to unfold quickly in a vertical direction, in the vertical contracting step, an upper region of the flattened airbag is tucked or invaginated into an interior of the airbag up to the distal end while folding up the two panels of the tucked region in layers on horizontal creases inside the airbag.
With the above way of folding the airbag, however, seams of the outer peripheral edges of the tucked region are folded up in piles with corrugations and in close contact to one another in a tight space between the two panels. In front and rear end regions of the tucked region, especially, the two panels of the tucked region overlap in a transverse direction of vehicle in multiple layers as well as the seams overlap in the transverse direction of vehicle in multiple layers and in close contact to one another, which results in bulkiness in the front and rear end regions of the folded-up airbag. Thus there is a need to reduce the folded-up configuration of the airbag.